Venting devices for electric storage cells



Feb. 24,1970 A. J. WHITE 3, 7,

VENTING DEVICES FOR ELECTRIC STORAGE CELLS Filed Oct. 6, 1967 INVENTORCHARLES A. J. WHH'E BY was 464mm AT'TORNEYS United States Patent3,497,104 VENTING DEVICES SELECTRIC STORAGE Charles Arthur John White,Redditch, England, assignor to Alkaline Batteries Limited, Redditch,England, a company of Great Britain Filed Oct. 6, 1967, Ser. No. 673,394Claims priority, application Great Britain, Oct. 10, 1966, 45,186/ 66Int. Cl. B65d 51/16; H01m 1/06 US. Cl. 22044 1 Claim ABSTRACT OF THEDISCLOSURE A venting device for an electric storage cell in the form ofa chamber, attached to the cell container, having at opposite ends awide inlet into the container and a narrow outlet venting to theatmosphere. The outlet is formed in a removable lid and is partiallyobstructed by a pin extending through the aperture and secured to thelid. The other end of the pin is attached to a spherical valve memberwhich rests on the surface of the inlet.

This invention relates to venting devices for electric storage cells,particularly though not exclusively alkaline storage cells.

According to the present invention an electric storage cell has aventing device comprising a chamber secured to the top of the cellcontainer with an inlet opening through the bottom of the chamber intothe container and an outlet to atmosphere formed in the top of thechamber, the overall area of the outlet being substantially less thanthat of the inlet; a valve member normally closes the inlet but ismovable by gas pressure to open positions in which it still obscures anydirect path from the inlet to the outlet.

Preferably the maximum cross-section of the valve member issubstantially greater than the area of either the inlet or the outlet,and the valve member is guided so as to remain substantially centrallylocated between the centers of the inlet and the outlet. Thus thechamber may be substantially symmetrical about a vertical axis e.g. itmay be cylindrical, the inlet and outlet being formed centrally in thetop and bottom of it.

Various forms of venting device have previously been employed inelectrical storage cells, including hinged flaps, spring loaded devices,and plugs with small venting holes. Especially in the case of alkalihydroxide electrolytes it is generally desirable to minimize access ofair since the electrolyte may become contaminated by absorption ofcarbon dioxide from the atmosphere. Moreover the surface tension ofalkali hydroxide electrolytes is such that metal surfaces are readilywetted, and bubbles are readily formed when gas is evolved from thesurface of the liquid. Hence, when a cell is gassing on charge, dropletsof electrolyte are liable to be carried away by the gases as bubbles anddeposited in the small vent orifice from which they may be blown outwith the gas.

In the preferred arrangement in accordance with the present invention,the inlet to the venting chamber is normally closed by the valve memberso as to reduce to a minimum passage of air from the cell container tothe atmosphere and vice-versa. When gassing occurs and the valve memberis lifted from the seating it opens a comparatively large inlet to thechamber so that any bubbles or droplets are unlikely to be projectedthrough it at a very high velocity. Moreover, any such bubbles passingthrough it cannot travel directly to the outlet but will first impingeeither On the valve member or on the sides of the chamber, so that theyare very unlikely to be carried out through the relatively small outlet.

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Preferably, the valve member is movably attached to a removable lidwhich forms the top of the chamber and in which the outlet is formed.Thus the lid can be removed and will carry the valve member with it soas to leave the inlet exposed for pouring liquid into the cellcontainer.

The lid is preferably formed of an elastomeric material integral with aflexible strap and a ring encircling the chamber to connect it thereto.Such an arrangement has no loose parts which are liable to be mislaid.

In a convenient construction the valve member is in the form of a ballmovably secured to the top of the chamber by a pin integral with thevalve member passing loosely through a hole in the top. In this case theclearance between the pin and the hole may form the outlet from thechamber. The pin is provided with a head, for example of arrow headform, which is sprung through the hole in the lid.

The invention may be put into practice in various ways but one specificembodiment suitable for use with an alkaline electric accumulator willbe described by way of example with reference to the accompanyingdrawings in which:

FIGURE 1 is a front elevation of the venting device,

FIGURE 2 is a sectional side elevation on the line A-A in FIGURE 1, and

FIGURE 3 is a plan view.

The venting device consists of a cylindrical metal chimney 10 adapted tobe attached to a filling hole in the top wall 11 of an accumulatorcasing and thus having an internal diameter of about 26 mm. in oneparticular case. The chimney can be attached to the filling hole bybeing a force fit in it or by suitable screw threads at its lower end orby welding.

The upper end of the chimney is closed by a removable lid 12 having askirt 14 with an internal rib 15 which is a snap fit into a groove 16 inthe outside of the chimney near its upper end. The lid is attached tothe chimney by a connecting strap 17 affording a hinge and by a ring 18.The lid, strap and ring are formed integrally from a suitableelastomeric material. The ring is spring fit into an annular grooveformed in the outside of the chimney adjacent its middle. A circularhole 20 about 4 mm. in diameter is formed in the center of the lid toprovide an outlet.

The lower end of the chimney is partly closed by an annular bottom wall21 which provides a large diameter inlet or seating 22 about 19 mm. indiameter, opening into the interior of the accumulator when the deviceis in position.

The lid, the chimney and the bottom wall provide a chamber, the axialdistance between the inside of the lid and the end wall being about 22mm.

Within this chamber is located a sphere 30 about 22 mm. in diameterprovided with a pin 31 about 3 mm. in diameter extending away from itaxially. At its end the pin has a head 32 formed as a straight sidedflat arrowhead. The sphere and the pin are formed integrally of asuitable synthetic plastics material. The pin, it will be noted, is aloose fit in the hole in the lid and it is the clearance between thehole in the lid and the pin which provides the outlet. The arrowhead onthe pin is a force fit through the hole in the lid and thus once it hasbeen pushed through the hole the sphere is attached to the lid. Thesphere, however, still has a certain freedom of movement both axiallyand from side to side.

In use, when gas is evolved in the accumulator, any rise in pressurewithin the casing lifts the sphere out of engagement with the seatingwhere it will normally rest under gravity provided the accumulator is inan upright position. The gas can then escape past the clearance betweenthe sphere and the chimney and thence to the atmosphere through theoutlet.

It will be appreciated that the dimensions of the device are such thatthe sphere always obscures any direct line of sight between the inletseating and the outlet opening and in this particular embodiment alsoobscures any axial line of sight between the lid and the inlet opening.The sphere thus acts as a battle to prevent droplets of moistureentrained in the escaping gases from reaching the outlet, or even thelid. The majority of the droplets will impinge on the sphere and dropback into the cell, and any which bounce off the sphere may be exepctedto be deflected onto the chimney or the end wall.

The inlet opening 22 is made as large as possible so that the velocityof gases passing through it is kept to a minimum and the force withwhich droplets of liquid are carried through the hole is lessened.

To add electrolyte to the cell the lid can be lifted off the chimney andthe sphere attached to the lid is thus withdrawn from the chamber. Thefact that the end wall opening is made as large as possible thenfacilitates the addition of electrolyte. 1

When the device is used with alkaline accumulators, which are liable toatmospheric contamination of the electrolyte, for example by carbondioxide, it is found that provided the restricted orifice is suitablysmall for the conditions, for example, having an effective crosssectionin the range 3 to 7 sq. mm., the rate of contamination of theelectrolyte is not excessive and can be tolerated.

An advantage which stems from this is that the sphere does not have toseal in the end wall opening which need not be flanged and manufacturingtolerances can be relaxed. Of course if atmospheric contamination is tobe minimized the sphere and the end wall opening can be made so as toform a seal and, in addition, a coiled light spring can be arrangedaround the pin to act on the inside of the lid and the upper half of thesphere so as to urge the sphere into engagement with the end wallopening.

It will be appreciated that the venting device in accordance with thepresent invention, while being an effective device in minimizing escapeof electrolyte but permitting escape of gasses generated in theaccumulator, and also keeping atmospheric contamination of theelectrolyte within acceptable limits, is an extremely simple device,easily and cheaply manufactured and assembled.

What I claim as my invention and desire to secure by Letters Patent is:

1. A venting and filling device for an electric storage cell,comprising; a cell container, a substantially cylindrical chambersecured to the top of the cell container with its axis vertical andincluding a valve seat formed in the bottom of said chamber and having acoaxial inlet opening into said container,

a removable lid member removably engaging the top of the chamber bymeans of a snap fit therewith, said lid member including a centrallylocated aperture, said lid member further including a flexible strap anda ring-like member for encircling said chamber to connect said lidmember thereto,

a substantially spherical valve member having a diameter slightly lessthan the internal diameter of the chamber but greater than said coaxialinlet opening, said valve member including an axially extending pinextending through said aperture and provided with a head portion largerthan said aperture to secure said valve member to said lid,

said pin being spaced from the walls of said aperture to provide a gasoutlet between its surface and the walls of said aperture.

References Cited 'UNITED STATES PATENTS 1,165,100 12/1915 Holland136-17-8 2,971,045 2/1961 August 136-178 FOREIGN PATENTS 5,266 8/1895Norway. 797,255 6/ 1958 Great Britain.

WINSTON A. DOUGLAS, Primary Examiner D. L. WALTON, Assistant Examiner

